absolute dating: Determining the number of years that have elapsed since an event occurred or the specific time when that event occurredatomic mass: The mass of an isotope of an electron, based on the number of protons and neutronsatomic nucleus: The assemblage of protons and neutrons at the core of an atom, containing almost all of the mass of the atom and its positive chargedaughter isotope: The isotope that forms as a result of radioactive decayelectrons: Negatively charged subatomic particles with very little mass; found outside the atomic nucleuselectron spin resonance: Method of measuring the change in the magnetic field, or spin, of atoms; the change in the spin of atoms is caused by the movement and accumulation of electrons from their normal position to positions in imperfections on the crystal structure of a mineral as a result of radiation.elements: Chemical substances that cannot be split into a simpler substancesfault: A fracture in a rock along which movement occursgeomagnetic polarity time scale: A record of the multiple episodes of reversals of the Earth’s magnetic polarity that can be used to help determine the age of rockshalf-life: The amount of time it takes for half of the parent isotopes to radioactively decay to daughter isotopesindex fossil: A fossil that can be used to determine the age of the strata in which it is found and to help correlate between rock unitsisotopes: Varieties of the same element that have the same number of protons, but different numbers of neutronsmagnetic field: A region where lines of force move electrically charged particles, such as around a magnet, through a wire conducting an electric current, or the magnetic lines of force surrounding the earthmagnetism: The force causing materials, particularly those made of iron and other certain metals, to attract or repel each other; a property of materials that responds to the presence of a magnetic fieldnormal polarity: Interval of time when the earth’s magnetic field is oriented so that the magnetic north pole is approximately in the same position as the geographic north poleneutrons: A subatomic particle found in the atomic nucleus with a neutral charge and a mass approximately equal to a protonoptical stimulating luminescence: Dating method that uses light to measure the amount of radioactivity accumulated by crystals in sand grains or bones since the time they were buriedpaleomagnetism: Remanent magnetization in ancient rocks that records the orientation of the earth’s magnetic field and can be used to determine the location of the magnetic poles and the latitude of the rocks at the time the rocks were formedparent isotope: The atomic nucleus that undergoes radioactive decay
polarity (magnetic polarity): The direction of the earth’s magnetic field, which can be normal polarity or reversed polaritypotassium-argon (K-Ar) method: Radiometric dating technique that uses the decay of 39K and 40Ar in potassium-bearing minerals to determine the absolute ageprinciple of cross-cutting relationships: Any geologic feature that cross-cuts across strata must have formed after the rocks they cut through were deposited.principle of faunal succession: Fossil species succeed each other in a definitive, recognizable order and once a species goes extinct, it disappears and cannot reappear in younger rocks.principle of original horizontality: Layers of strata are deposited horizontally, or nearly horizontally, and parallel or nearly parallel to the earth’s surface.principle of superposition: In an undeformed sequence, the oldest rocks are at the bottom and the youngest rocks are at the top.protons: Positively charged subatomic particles found in the nucleus of an atomradioactivity (radioactive): An unstable isotope spontaneously emits radiation from its atomic nucleusradioactive decay: The process by which unstable isotopes transform to stable isotopes of the same or different elements by a change in the number of protons and neutrons in the atomic nucleusradiocarbon dating: Radiometric dating technique that uses the decay of 14C in organic material, such as wood or bones, to determine the absolute age of the material

radiometric dating: Determination of the absolute age of rocks and minerals using certain radioactive isotopesrelative dating: Rocks and structures are placed into chronological order, establishing the age of one thing as older or younger than another
reversals (magnetic reversals): Changes in the earth’s magnetic field from normal polarity to reversed polarity or vice versareversed polarity: Interval of time when the earth’s magnetic field is oriented so that magnetic north pole is approximately in the same positions as the geographic south polestrata (singular: stratum): Distinct layers of sediment that accumulated at the ea surface.stratigraphy: The study of strata and their relationshipsthermoluminescence: Dating method that uses heat to measure the amount of radioactivity accumulated by a rock or stone tool since it was last heated.

DEFORMATION TWINNING
Lattice gliding due to stress subjected to a crystal. Twinned crystals may show deformation lamellae. Twinning in crystals may be caused by shock deformation.

DENSITY vs ROCK TYPE

Rock Type

Grams / milliliter (mL)

Granite

2.8

Sandstone

2.6

Basalt or lava rock

3.1

Hematite

5.1

Stony meteorite

3.5

Iron meteorite

8.0

DIAMOND
The crystalline form of carbon (C) is the hardest naturally occurring material. May be formed in meteorite impact when carbon, e.g. in graphite-bearing rocks, is subjected to extraordinarily high temperatures and pressures. Is observed in meteorites and impactites (e.g., Younger Dryas event, Ries, Popigai impact structures).

Asteroid Impact Diamonds: Diamonds have been found in and around the craters of many asteroid impact sites. Earth has been repeatedly hit by asteroids throughout its history. These asteroids hit with such force that pressures and temperatures high enough to form diamonds are produced. If the target rock contains carbon, the conditions needed to form diamonds might occur within the impact area.Extraterrestrial Diamonds: Diamonds have been discovered in some meteorites. These diamonds are thought to have formed in space in response to asteroid impacts or other severe events.